TRD4. Design and Engineering of MicroED hardware for nanocrystallization and time resolved studies ? Spence (Lead) Summary The initial development of microcrystal electron diffraction (MicroED), and subsequent improvements to the technique, have been driven by new data collection methods and hardware for controlling the microscope. Of particular importance is turning MicroED into a high-throughput method with time-resolved capability to be able to rapidly determine time-dependent structure-function relation of functioning macomolecular complexes. This will propel the technique forward, but it requires additional design and engineering efforts in order to make these desired features a reality. Here, we will focus on three MicroED engineering aims: (1) the development of high throughput on-grid crystallization equipment to increase the efficiency and success rate of MicroED experiments, (2) the adaptation and design of new equipment and methods to conduct time-resolved MicroED experiments, (3) the design of a multi-functional grid surface, or ?lab on a grid? for the streamlined preparation of small molecule samples for MicroED structure determination. The aims of this project are 1. Development of high throughput on-grid crystallization for MicroED; 2. New sample preparation methodology for time-resolved MicroED; 3. ?Lab on a grid? for MicroED analysis of small molecules. Overall, we will design, engineer, and implement new tools and techniques for three major aspects of MicroED. These new tools will greatly accelerate the throughput capabilities of the MicroED and improve the quality of collected data. Additionally, new experimental modalities will be made possible through the work in Aim 2, opening the door to precise time-resolved studies by MicroED.